如何使用AT命令、vb.Net发送长消息

Imports System.IO.Ports

Public Class MainForm
    Dim serialPort As New SerialPort()

    Private Sub MainForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ' 设置串口参数
        serialPort.PortName = "COM1" ' 串口号
        serialPort.BaudRate = 9600 ' 波特率
        serialPort.Parity = Parity.None ' 校验位
        serialPort.DataBits = 8 ' 数据位
        serialPort.StopBits = StopBits.One ' 停止位

        ' 打开串口
        Try
            serialPort.Open()
        Catch ex As Exception
            MessageBox.Show("无法打开串口：" & ex.Message)
        End Try
    End Sub

    Private Sub SendLongMessage(message As String)
        ' 设置短信模式
        serialPort.WriteLine("AT+CMGF=1")

        ' 设置短信中心号码
        serialPort.WriteLine("AT+CSCA=""+1234567890""")

        ' 发送短信内容
        serialPort.WriteLine("AT+CMGS=""" & message & """")

        ' 等待输入短信内容
        Threading.Thread.Sleep(1000)

        ' 发送Ctrl+Z表示结束短信输入
        serialPort.Write(Chr(26))
    End Sub

    Private Sub SendButton_Click(sender As Object, e As EventArgs) Handles SendButton.Click
        Dim message As String = MessageTextBox.Text
        SendLongMessage(message)
    End Sub
End Class